1. |
- Afshar, Mastaneh, et al.
(author)
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Complete Genome Sequences of Two Staphylococcus saccharolyticus Strains Isolated from Prosthetic Joint Infections
- 2021
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In: Microbiology Resource Announcements. - : American Society for Microbiology. - 2576-098X. ; 10:10
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Journal article (peer-reviewed)abstract
- Staphylococcus saccharolyticus is a human skin bacterium and is occasionally associated with prosthetic joint infections (PJIs). Here, we report the complete genome sequences of two strains that were isolated from shoulder and hip PJIs. The genomes show signs of reductive evolution; around 21% of all coding sequences are inactivated by frameshift mutations.
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2. |
- Ahle, Charlotte M., et al.
(author)
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Staphylococcus saccharolyticus : An Overlooked Human Skin Colonizer
- 2020
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In: Microorganisms. - : MDPI. - 2076-2607. ; 8:8
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Journal article (peer-reviewed)abstract
- Coagulase-negative staphylococcal species constitute an important part of the human skin microbiota. In particular, facultative anaerobic species such as Staphylococcus epidermidis and Staphylococcus capitis can be found on the skin of virtually every human being. Here, we applied a culture-independent amplicon sequencing approach to identify staphylococcal species on the skin of healthy human individuals. While S. epidermidis and S. capitis were found as primary residents of back skin, surprisingly, the third most abundant member was Staphylococcus saccharolyticus, a relatively unstudied species. A search of skin metagenomic datasets detected sequences identical to the genome of S. saccharolyticus in diverse skin sites, including the back, forehead, and elbow pit. Although described as a slow-growing anaerobic species, a re-evaluation of its growth behavior showed that S. saccharolyticus can grow under oxic conditions, and, in particular, in a CO2-rich atmosphere. We argue here that S. saccharolyticus was largely overlooked in previous culture-dependent and -independent studies, due to its requirement for fastidious growth conditions and the lack of reference genome sequences, respectively. Future studies are needed to unravel the microbiology and host-interacting properties of S. saccharolyticus and its role as a prevalent skin colonizer.
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3. |
- Ahlstrand, Erik, 1974-, et al.
(author)
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Alteration of the colonization pattern of coagulase-negative staphylococci in patients undergoing treatment for hematological malignancy
- 2012
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In: European Journal of Clinical Microbiology and Infectious Diseases. - New York, USA : Springer. - 0934-9723 .- 1435-4373. ; 31:7, s. 1679-1687
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Journal article (peer-reviewed)abstract
- The aim was to prospectively describe the colonization pattern of coagulase-negative staphylococci (CoNS) and the relationship between colonizing and invasive CoNS isolates among patients undergoing treatment for hematological malignancy. Fourteen newly diagnosed patients were included with either multiple myeloma or acute leukemia. Patients were repeatedly sampled from nares, throat, axillae, and perineum, and the CoNS isolates obtained were phenotypically characterized together with blood isolates of CoNS using the PhenePlate system (PhP). During the treatment a gradual reduction in the heterogeneity of colonizing CoNS was observed as well as an inter-patient accumulation of phenotypically related and multi-drug-resistant CoNS. These clusters of CoNS persisted for 2–3 months after the end of therapy. Ten positive blood cultures of CoNS were obtained and in the majority of these cases CoNS of the same PhP type were found in superficial cultures collected prior to the blood culture sampling. In conclusion, the study shows that therapy for hematological malignancy is associated with a homogenization of colonizing CoNS isolates and that this acquired flora of CoNS is persistent several months after the end of therapy. Furthermore, the results suggest that the source of bloodstream infections of CoNS in hematological patients is colonizing CoNS of the skin and mucosa.
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4. |
- Ahlstrand, Erik, 1974-
(author)
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Coagulase-negative staphylococci in hematological malignancy
- 2013
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Doctoral thesis (other academic/artistic)abstract
- Bacterial infections are common in hematological malignancy. Coagulase-negative staphylococci (CoNS) are among the most prevalent causes of bacteremia in patients with hematological malignancies.In this thesis, different aspects of CoNS in hematological malignancy have been studied in four papers:In paper 1, CoNS blood culture isolates from patients with hematological malignancies treated at the University Hospital of Örebro from 1980 to 2009 were revaluated for the presence of reduced sensitivity to glycopeptides. A high incidence of heterogeneous-intermediate glycopeptide resistance was observed and there was a trend towards increasing incidence of this phenotype over time.In paper 2, the colonization pattern of CoNS among patients undergoing intensive chemotherapy for hematological malignancy was investigated. A successive homogenization and an accumulation of CoNS phenotypes mutually present in a majority of included patients were demonstrated.In paper 3, a PCR method to determine the clinical significance of positive blood cultures of the CoNS species Staphylococcus epidermidis was evaluated. The test failed to discriminate bloodstream infection from blood culture contamination.Finally, in paper 4, the long-term molecular epidemiology of S. epidermidis blood culture isolates from patients with hematological malignancies was studied with multilocus sequence typing. A predominance of sequence type 2 was demonstrated during the entire 30 year study period.In conclusion, the results are consistent with that CoNS have established as important pathogens by its capacity to colonize the human skin, its ability to reside and spread in the hospital environment and its rapid adaptation to stressors such as antimicrobials.
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5. |
- Ahlstrand, Erik, 1974-, et al.
(author)
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Evaluation of a PCR method to determine the clinical significance of blood cultures with Staphylococcus epidermidis in patients with hematological malignancies
- 2014
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In: Acta Pathologica, Microbiologica et Immunologica Scandinavica (APMIS). - : Wiley-Blackwell. - 0903-4641 .- 1600-0463. ; 122:6, s. 539-544
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Journal article (peer-reviewed)abstract
- The aim was to investigate whether the detection and quantification of Staphylococcus epidermidis DNA in blood could distinguish S. epidermidis blood stream infections (BSIs) from blood culture contaminations in patients with hematological malignancies. The hld gene was chosen to identify S. epidermidis DNA and DNA in blood samples was detected by real-time PCR. Blood samples were obtained simultaneously with blood cultures positive for S. epidermidis (n = 30), during blood culture-negative episodes (n = 10) and episodes of bacteremia with other bacteria than S. epidermidis (n = 4) and from healthy blood donors (n = 10). In addition, DNA from S. epidermidis and a selection of other bacterial species were analyzed. Three different sets of criteria were used to classify episodes with positive blood cultures with S. epidermidis as BSIs or contaminations. All DNA preparations from S. epidermidis (n = 48) were hld-positive, but other bacterial species (n = 13) were negative. Sixteen (53%) of 30 blood samples from patients with blood cultures positive for S. epidermidis were hld-positive, but none of the controls. There was no clear association between a positive hld PCR and episodes interpreted as BSIs. In conclusion, hld PCR failed to distinguish S. epidermidis BSIs from blood culture contaminations in patients with hematological malignancies.
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6. |
- Ahlstrand, Erik, et al.
(author)
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Glycopeptide resistance in coagulase-negative staphylococci isolated in blood cultures from patients with hematological malignancies during three decades
- 2011
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In: European Journal of Clinical Microbiology and Infectious Diseases. - : Springer Science and Business Media LLC. - 0934-9723 .- 1435-4373. ; 30:11, s. 1349-1354
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Journal article (peer-reviewed)abstract
- The aim of this study was to determine if there was a long-term increase in glycopeptide minimum inhibitory concentration (MIC) values, MIC creep, among bloodstream isolates of Staphylococcus epidermidis and S. haemolyticus isolated from patients with hematological malignancies. We conducted a retrospective single-center study where all positive blood cultures of S. epidermidis (n = 387) and S. haemolyticus (n = 19) isolated from patients with hematological malignancies during three decades, 1980 to 2009, were re-evaluated for the presence of reduced susceptibility to vancomycin and teicoplanin. Three different methods for the detection of reduced susceptibility to glycopeptides were used; standard Etest, macromethod Etest, and glycopeptide resistance detection (GRD) Etest. The median MIC value for vancomycin was 2 mg/L. MIC values for vancomycin and teicoplanin did not show any statistically significant increase during the study period. The presence of heterogeneously glycopeptide-intermediate staphylococci (hGIS) was analyzed among 405 coagulase-negative staphylococci (CoNS) isolates. hGIS were found in 31-45% of the CoNS isolates by the macromethod Etest and in 53-67% by the GRD Etest during the three decades. In conclusion, we did not observe any long-term glycopeptide MIC creep determined by the standard Etest, although a high and increasing proportion of heterogeneous vancomycin resistance was observed.
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7. |
- Ahlstrand, Erik, et al.
(author)
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Long-term molecular epidemiology of Staphylococcus epidermidis blood culture isolates from patients with haematological malignancies
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Other publication (other academic/artistic)abstract
- Staphylococcus epidermidis is an important cause of bloodstream infections in patients with haematological malignancies. Knowledge of the long-term epidemiology of these infections is limited. We surveyed all S. epidermidis blood culture isolates from patients treated for haematological malignancies at the University Hospital of Örebro, Sweden from 1980 to 2009. A total of 373 S. epidermidis isolates were identified and multilocus sequence typing and standard antibiotic susceptibility testing were employed to characterize these isolates. The majority of the isolates 361/373 (97%) belonged to clonal complex 2, and the 373 isolates were divided into 45 sequence types (STs); Simpson’s Diversity Index was 0.56. The most prevalent STs were ST2 (243/373, 65%) and ST215 (28/373, 8%). These two STs were isolated during the entire study period, and together caused temporal peaks in the incidence of positive blood cultures of S. epidermidis. Methicillin resistance was detected in 213/273 (78%) of all isolates. In the two predominating STs, ST2 and ST215, the proportion of methicillin resistance was 257/271 (95%); 234/271 (86%) displayed a multidrug-resistant phenotype. In conclusion, in this long-term study of patients with haematological malignancies, we demonstrate a predominance of methicillin-resistant ST2 among S. epidermidis blood culture isolates.
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8. |
- Ahlstrand, Erik, 1974-, et al.
(author)
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Long-term molecular epidemiology of staphylococcus epidermidis blood culture isolates from patients with hematological malignancies
- 2014
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In: PLOS ONE. - San Francisco, USA : Public Library Science. - 1932-6203. ; 9:6
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Journal article (peer-reviewed)abstract
- Staphylococcus epidermidis is an important cause of bloodstream infections in patients with hematological malignancies. Knowledge of the long-term epidemiology of these infections is limited. We surveyed all S. epidermidis blood culture isolates from patients treated for hematological malignancies at the University Hospital of Orebro, Sweden from 1980 to 2009. A total of 373 S. epidermidis isolates were identified and multilocus sequence typing, staphylococcal chromosome cassette mec (SCCmec) typing and standard antibiotic susceptibility testing were employed to characterize these isolates. The majority of the isolates 361/373 (97%) belonged to clonal complex 2, and the 373 isolates were divided into 45 sequence types (STs); Simpson's Diversity Index was 0.56. The most prevalent STs were ST2 (243/373, 65%) and ST215 (28/373, 8%). Ninety three percent (226/243) of the ST2 isolates displayed either SCCmec type III or IV. ST2 and 215 were isolated during the entire study period, and together these STs caused temporal peaks in the number of positive blood cultures of S. epidermidis. Methicillin resistance was detected in 213/273 (78%) of all isolates. In the two predominating STs, ST2 and ST215, methicillin resistance was detected in 256/271 isolates (95%), compared with 34/100 (34%) in other STs (p<0.001). In conclusion, in this long-term study of patients with hematological malignancies, we demonstrate a predominance of methicillin-resistant ST2 among S. epidermidis blood culture isolates.
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9. |
- Al Janabi, Jasmina, et al.
(author)
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Emerging resistance in Staphylococcus epidermidis during dalbavancin exposure : a case report and in vitro analysis of isolates from prosthetic joint infections
- 2023
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In: Journal of Antimicrobial Chemotherapy. - : Oxford University Press. - 0305-7453 .- 1460-2091. ; 78:3, s. 669-677
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Journal article (peer-reviewed)abstract
- BACKGROUND: Dalbavancin, a semisynthetic lipoglycopeptide with exceptionally long half-life and Gram-positive spectrum, is an attractive option for infections requiring prolonged therapy, including prosthetic joint infections (PJIs).OBJECTIVES: To investigate the prevalence of reduced susceptibility to dalbavancin in a strain collection of Staphylococcus epidermidis from PJIs, and to investigate genomic variation in isolates with reduced susceptibility selected during growth under dalbavancin exposure.METHODS: MIC determination was performed on S. epidermidis isolates from a strain collection (n = 64) and from one patient with emerging resistance during treatment (n = 4). These isolates were subsequently cultured on dalbavancin-containing agar and evaluated at 48 h; MIC determination was repeated if phenotypical heterogeneity was detected during growth. Population analysis profile (PAP-AUC) was performed in isolates where a ≥ 2-fold increase in MIC was detected, together with corresponding parental isolates (n = 21). Finally, WGS was performed.RESULTS: All strains grew at 48 h on agar containing 0.125 mg/L dalbavancin. PAP-AUC demonstrated significant differences between parental and derived strains in four of the eight analysed groups. An amino acid change in the walK gene coinciding with emergence of phenotypic resistance was detected in the patient isolates, whereas no alterations were found in this region in the in vitro derived strains.CONCLUSIONS: Exposure to dalbavancin may lead to reduced susceptibility to dalbavancin through either selection of pre-existing subpopulations, epigenetic changes or spontaneous mutations during antibiotic exposure. Source control combined with adequate antibiotic concentrations may be important to prevent emerging reduced susceptibility during dalbavancin treatment.
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10. |
- Asfaw Idosa, Berhane, PhD, 1977-, et al.
(author)
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C10X polymorphism in the CARD8 gene is associated with bacteraemia
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Other publication (other academic/artistic)abstract
- Introduction:: The NLRP3 inflammasome is an intracellular multi-protein complex that triggers caspase-1 mediated maturation of interleukin-1β (IL-1β); one of the most potent mediators of inflammation and a major cytokine produced during severe infections, like sepsis. However, the excessive cytokine levels seem to stage for tissue injury and organ failure, and high levels of IL-1β correlates with severity and mortality of sepsis. Instead, recent data suggest caspase- 1 to function as a guardian against severe infections. CARD8 has been implied to regulate the synthesis of IL-1β via interaction to caspase-1. In recent years, polymorphism of CARD8 (C10X) per se or in combination with NLRP3 (Q705K) has been implicated with increased risk of inflammation. The aim was to investigate the correlation of these polymorphisms with severe blood stream infection.Methods:: Human DNA was extracted from blood culture bottles that were found to be positive for microbial growth (i.e. patients with bacteraemia). Polymorphisms Q705K in the NLRP3 gene and C10X in the CARD8 gene were genotyped using TaqMan genotyping assay. The results were compared to healthy controls and to samples from patients with negative cultures.Results:: The polymorphism C10X was significantly over-represented among patients with bacteraemia as compared to healthy controls, whereas patients with negative blood culture were not associated with a higher prevalence. No association was observed with polymorphism Q705K of NLRP3 in eithergroup of patients.Conclusions:: Patients carrying polymorphism C10X in the CARD8 gene are at increased risk of developing bacteraemia and severe inflammation.
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